pos/main.py

#!/usr/bin/env python3

import socket
import struct
import sys
import libevdev
#from libevdev import ecodes

def main(device_path, dest_ip, dest_port):
    """
    Reads absolute X and Y coordinates from an evdev device and sends them
    over UDP to a specified address and port.

    Args:
        device_path (str): The path to the input event device 
                           (e.g., /dev/input/event0).
        dest_ip (str): The destination IP address.
        dest_port (int): The destination port.
    """
    try:
        # Open the evdev device in a non-blocking way
        fd = open(device_path, 'rb')
        d = libevdev.Device(fd)
        print(f"Successfully opened device: {d.name}")


        print("Listening for ABS_X and ABS_Y events. Press Ctrl+C to exit.")

        # Create a UDP socket
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        print(f"Sending coordinates to {dest_ip}:{dest_port}")

        # Variables to store the latest coordinates
        x_coor = None
        y_coor = None

        # Loop indefinitely to read events
        while True:
            for e in d.events():
                # We are only interested in absolute axis events
                if e.type == libevdev.EV_ABS:
                    if e.code in [libevdev.EV_ABS.ABS_X,libevdev.EV_ABS.ABS_MT_POSITION_X]:
                        x_coor = e.value
                    elif e.code in [libevdev.EV_ABS.ABS_Y,libevdev.EV_ABS.ABS_MT_POSITION_Y]:
                        y_coor = e.value

                # When we have both coordinates, send them
                if x_coor is not None and y_coor is not None:
                    print(f"Read coordinates: X={x_coor}, Y={y_coor}")
                    
                    # Pack the two 16-bit unsigned integers into a buffer.
                    # The format string 'HH' specifies two unsigned short integers (u16).
                    # The '<' character ensures little-endian byte order.
                    try:
                        packet = struct.pack('<HH', int((float(x_coor)/32767.0)*1920), int((float(y_coor)/32767.0)*1080))
                        
                        # Send the packet over UDP
                        sock.sendto(packet, (dest_ip, dest_port))
                        print(f"Sent {len(packet)} bytes.")

                        # Reset coordinates to wait for the next pair of events
                        x_coor = None
                        y_coor = None

                    except struct.error as se:
                        print(f"Error packing data: {se}. Coordinates might be out of range for u16 (0-65535).")
                    except socket.error as soe:
                        print(f"Socket error: {soe}")


    except FileNotFoundError:
        print(f"Error: Device not found at {device_path}")
        print("Please ensure you have the correct event device path.")
    except PermissionError:
        print(f"Error: Permission denied for {device_path}.")
        print("This script usually needs to be run with root privileges (e.g., 'sudo python3 script.py')")
    except KeyboardInterrupt:
        print("\nExiting.")
    finally:
        if 'fd' in locals() and not fd.closed:
            fd.close()
        if 'sock' in locals():
            sock.close()

if __name__ == "__main__":
    if len(sys.argv) != 4:
        print("Usage: python3 evdev_udp_sender.py <device_path> <dest_ip> <dest_port>")
        print("Example: sudo python3 evdev_udp_sender.py /dev/input/event4 127.0.0.1 12345")
        sys.exit(1)

    device = sys.argv[1]
    ip = sys.argv[2]
    try:
        port = int(sys.argv[3])
        if not (0 < port < 65536):
            raise ValueError
    except ValueError:
        print("Error: Port must be an integer between 1 and 65535.")
        sys.exit(1)
        
    main(device, ip, port)